'OBD' related articles 1

DescriptionAlmost all new automobiles produced today are required, by law, to provide an interface from which test equipment can obtain diagnostic information.The data transfer on these interfaces follow several standards, none of which are directly compatible with PCs or PDAs. The ELM327 is designed to act as a bridge between these On-Board Diagnostics (OBD) ports and standard RS232 ports.The ELM327 builds on improved versions of our proven ELM320, ELM322, and ELM323 interfaces by adding seven CAN protocols to them. The result is an IC that can automatically sense and convert the most common protocols in use today. There are a number of other improvements as well – a high speed RS232 option, battery voltage monitoring, andcustomizable features through programmable parameters, to name only a few.The ELM327 requires few external components to make a fully functioning circuit. The followingpages discuss the interface details, and show how to use the IC to ‘talk’ to your vehicle, then concludes with two schematics to get you started.